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A noob who struggles with train signals (added save file)

Posted: Mon Apr 05, 2021 10:11 pm
by SimpCommander
Hello!

I've just started playing Factorio last week and i've been looking at multiple guides about trains in Factorio (including kathrine of sky on YouTube). But i can't get it to work. After multiple hours i got my oil train to work, but i can't seem to get my stone train to work. I could probably just add 2 lanes everywhere but i would like to understand why it doesn't work before i do that.

The train gives me the error code "stop is inaccessible from current position" but when i try to run it manually it works fine. I have re-done all my signals countless times so i have no idea whats wrong.

Since it's hard to explain, i've added my save file.

Re: A noob who struggles with train signals (added save file)

Posted: Tue Apr 06, 2021 12:11 am
by Serenity
SimpCommander wrote:
Mon Apr 05, 2021 10:11 pm
but when i try to run it manually it works fine
Signals don't matter in manual mode. They are for automatic trains.

Re: A noob who struggles with train signals (added save file)

Posted: Tue Apr 06, 2021 2:03 am
by astroshak
I have not looked at your save file.

However, I do have some questions to ask you.

Are your train stations on the correct side of the track? They must be on the right (not the left) side of the track from the train’s perspective.

What type of train stations are you using? Are they pull in and back out stations? Or are they pull forward in, and then pull forward to some kind of turn-around before headed back stations?

Those two questions stem from the “inaccessible from the current location” message you are getting.

If the train only has one Locomotive, but you want the train to back out of the station, then you need a second Locomotive, facing backward, somewhere (ideally at the tail end) in the train. Locomotives can only move trains in one direction, they do NOT have a reverse. That’s what the second Locomotive, facing backward, is for.

If the train stop is on the wrong side of the track, then there may not be any way by which the train can reach that stop, either because the rails to get there the way it wants to don’t exist, or because of improper signaling. To diagnose this, open the Locomotive’s window, and hold CTRL down while you move the mouse around in that window. You can even hold the Left Mouse Button down to “grab” the map for scrolling purposes. You will see the path highlighted in the window, up until the point where it cannot continue. That will tell you where you have an improperly placed signal, or “missing” track.

Speaking of signals, if the track is intended to be two way - think a one lane road where cars travel both directions down it - then any and all signals placed on the track MUST have a signal directly opposite them on the track. If the signals are misplaced even one space off, then the track is off limits to the automatic mode trains, and can only be traversed by trains in manual mode. Such tracks are exceedingly simple to set up if all you have is one train on that track (other tracks crossing this one are fine, but not merging). Such tracks are also, however, a pain to set up properly when multiple trains are involved. It is far simpler, though more costly, to use a two track system. To continue the road analogy, think a divided highway, where all traffic going one way is on one side of the highway, and all traffic going the other way is on the opposite side of the highway.

Re: A noob who struggles with train signals (added save file)

Posted: Tue Apr 06, 2021 5:10 am
by SoShootMe
SimpCommander wrote:
Mon Apr 05, 2021 10:11 pm
I've just started playing Factorio last week and i've been looking at multiple guides about trains in Factorio (including kathrine of sky on YouTube). But i can't get it to work. After multiple hours i got my oil train to work, but i can't seem to get my stone train to work. I could probably just add 2 lanes everywhere but i would like to understand why it doesn't work before i do that.
astroshak wrote:
Tue Apr 06, 2021 2:03 am
To diagnose this, open the Locomotive’s window, and hold CTRL down while you move the mouse around in that window.
This is an excellent technique for solving "No path" issues. As well as dragging the map view, you can also zoom which should allow you to identify the exact location of the problem. @SimpCommander, in case you're still stuck:
it should quickly reveal an "unpaired" signal near the junction by Stone 1, preventing the train there finding a path to Stone Unload. Also at the other end of the stretch of bidirectional track, affecting the same train in the opposite direction.


Unfortunately, the technique doesn't help with with other signal issues, most importantly those that may result in deadlock. Broadly speaking, to avoid the possibility of deadlock with bidirectional track, you should use chain signals except for a signal passed when a train leaves a block containing bidirectional track and enters one containing only unidirectional track or a train stop - this is not the case near near Oil 1. Signals at intervals along a stretch of unidirectional track are useful to improve throughput by allowing one train to follow another, but along bidirectional track they may cause trains to deadlock facing each other (if rail signals) or are redundant (if chain signals) - this applies between the junction north of Oil 1 and the one south of Stone 1.